Have a question on a HKS BOV???????

[IndigoMKII]

Because the system was designed on having it recirculated. The afm meters the air before the turbo. Once the bov releases the air it goes back into the intake before the turbo after the afm. If the air is not put back in, it causes a rich condition Becuase the computer monitored the air and added fuel to make up for it so if it doesn't receive the air it "thinks" it's going to it runs rich and causes it to stall Becuase the air was not there to burn the fuel.

I'm well aware of how a closed system works. What I'm saying is I don't think that by changing one thing such as releasing metered air is going to cause the entire system to stall.

Take a running engine, now spray carb cleaner into that engine. What happens? The engine chugs for a little bit but clears back up. I know if you continue to spray carb cleaner into the engine, it will eventually stall. There's no way just the BOV can cause it to stall, especially from higher RPMs as the ECU cuts power to the injectors on decel.

 

[suprasick]

On my other Supra I had years ago, it came with a greddy type s vented to the atmosphere. It only stalled under certain conditions. If I remember correctly, it was when under boost at WOT under 3k rpms and then suddenly put it in neutral. There was also a TON of black smoke between shifts. As of now, I just recirculate it.

 

[TaylorRacing]

So before the stall are you getting compressor surge?

 

[Poodles]

Like I said, depends on the situation. On a bone stock car, it's probably fine. On a car with turbo back exhaust pushing right below fuel cut and it hits full boost at 3K RPM, it's going to be an issue...

 

[Backlash2032]

Poodles. Think about the situation and all of the inputs into the ECU. Yeah, the AFM is going to say that there is more air than is actually going into the engine, because you vented some of it to the atmosphere. But the throttle plate is going to snap shut, making the TPS idl contacts close, and the ECU is going to engage fuel cut because the engine speed is over 1600 rpm and the air flow signal is WAY higher than it "should be". This is why our cars don't gurgle on decel. Because there is no fuel being introduced into the engine! Because of the TPS idl contacts being closed! That is the same reason that a vented bov with a properly adjusted TPS should not cause stalling issues. My TPS is slightly off, and I still never stall. I may bog slightly from 2500 rpm light boost to neutral, but I don't remember the last time I stalled.

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[Poodles]

Your theory would only be correct if our engine was direct injected. It's not.

 

[Backlash2032]

How does the engine being direct injected or not have anything to do with it?

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[Poodles]

The fuel is delivered directly to the cylinders meaning it is instantly turned off or on. It MIGHT work if we had sequential injection (we don't), but the general point is that yes you're flooding it and the more air (i.e. boost) you were just sucking into the motor, the more fuel is being injected.

Port fuel injection (especially when it isn't sequential) is still a very inaccurate fuel delivery method, hence the adjustments and workarounds the OEMs use...

 

[suprafreak123]

Sooo!!!! guys it has not stall during rapid deceleration or blows black smoke through gears.

 

[suprafreak123]

Im thinking of buying the turbosmart Dual port BOV and go 50/50 on it.Sounds Sweet!!!!!!

 

[Backlash2032]

The fuel is delivered directly to the cylinders meaning it is instantly turned off or on. It MIGHT work if we had sequential injection (we don't), but the general point is that yes you're flooding it and the more air (i.e. boost) you were just sucking into the motor, the more fuel is being injected.

Port fuel injection (especially when it isn't sequential) is still a very inaccurate fuel delivery method, hence the adjustments and workarounds the OEMs use...

My car has 3 inch exhaust without a cat, so its really easy to tell if the the engine is being supplied with fuel or not. The ECU may shut power off (I guess ground technically but whatever) to the injectors, but there is a tiny bit of residual fuel. There always is. Just like when I let off the gas there's a little gurgle of fuel in the exhaust.. it will be the same way with a vented bov

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[Poodles]

You're missing the point...

 

[Trent]

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Like I said, depends on the situation. On a bone stock car, it's probably fine. On a car with turbo back exhaust pushing right below fuel cut and it hits full boost at 3K RPM, it's going to be an issue...

I certainly don't mean to argue, but in my experience with these cars, this is not true entirely. I have sold and installed countless vented to atmosphere BOV's on MK3's in my time working for SupraSport in the late 90's and then with MVP and PHR in 2003-2005. Everything from pretty much stock cars all the way up to my 450rwhp car and others similar (all still with AFM) and we never had stalling issues with these cars. Now truth be told, back then, most of the BOV's had adjustment screws on them and you could tighten them if the car was having a hard time with this, but I did so many of them, I knew where the screws needed to be.

My 88 made 400-450rwhp for 3 years before going to a MAP setup and I never had a stalling issue. I had the Greddy type S, the HKS SSQV, The Greddy Type R, and ultimately the HKS Racing. Never a problem.

On my current 89 it came with a genuine HKS SSQ and did not stall either. I have changed that to a genuine Tial BOV since, but have not driven the car since that change.

I wholeheartedly believe that most people who have issues with stalling also have other issues elsewhere. Whether that be a less than healthy engine, small leaks in plumbing, TPS/ISC calibration or health, AFM sensor condition, etc etc etc etc.

Just my 15 years of 2psi, no offense or argument intended

 

[IndigoMKII]

​

I wholeheartedly believe that most people who have issues with stalling also have other issues elsewhere. Whether that be a less than healthy engine, small leaks in plumbing, TPS/ISC calibration or health, AFM sensor condition, etc etc etc etc.

Exactly what I'm trying to say. No way can this one problem cause a healthy engine to stall, other things must be factored in to aid in that.

 

[Backlash2032]

You're missing the point...

Then please elaborate. Because I'm clearly missing something lol

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[Poodles]

http://www.supramania.com/forums/sh...n-venting-BOV-to-atmosphere&highlight=dashpot

Why would someone go through all this trouble if there wasn't an issue to begin with? Most of us just learned to drive around the quirk, not actually fix it (i.e. clutch in, blip throttle when coming to a stop)

 

[Backlash2032]

If it wasn't so salty out, I would go make a video of my car doing full boost to neutral with no personal intervention to show that there isn't a problem...

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